Lightning-arrester.



J. R. McFARLIN.

Patented Aug. 27, 1918'.

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l. R. McFARLIN.

LIGHTNING ARRESTER.

APPLICATIQN man not. 26, 191s.

' 1,277,095. Patented Aug. 27, 1918,

2 SHEETSSHEEI 2 UNITED STATES PATENT OFFICE oH ROBERT McFARLIN, or PHILADELPHIA, rEN sYLvANIA, AssIGNoit To E ECTRIC snnvrcn' SUPPLIES COMPANY, or PHILADELPHIA, PENNSYLVANIA, A coRroRA TION or r NNsYLvANIA.

LIGHTNING-ARRESTER.

Specification of Letters Patent. -Pate1 ted Aug; 27, 1918,

1 Applicationfi1ed0cto1ier.26, 1916.. Serial 127,798.

. To all whom it Mal/concern:

Be it knownthat I, JOHN R. MCFARLIN, a citizen of the United States, residing in the city of Philadelphia county of Philadelphia, and State of Fennsylvania, have in vented certainlmprovements in Lightning- ,wires to ground;

Arresters, ofwhich the following is a specification. i v

I My [invention relates to lightning arresters of the expulsion type and my leading object isto. protect'lelectric apparatus ,irom lightning and other high voltageby trodes at the outlet from the housing, the air expanded the heat being drawn to a restricted annular passage formingv an expulsion gap between; the electrodes and exerting the desired, force of such character as' to effectively interrupt the flow of currentto sr n 1,, g

A desideratum attained by my invention is a high degree of; efficiency combined with flexibility which admits of the readyadjustment of the apparatus so that it will operate efiiciently under varying conditions.

In this arrester the air gap distance is so adjusted that normal line potential will not break it down and are over, but a rise of potential slightly higher than the normal will, hence maximum protection to the apparatus is afi'orded.

The characteristic features of my improvements willmore fully appear from the following description and the accompanying drawings in illustration thereof.

In the drawings, Figure 1 is a side elevation of apparatus embodying my invention; Fig. 2 is a broken top plan view of the same; Fig. 3 is a broken bottom plan View; Fig.4 is a sectional view on the line 441 of Fig. 2; Fig. 5 is a sectional view on the line 5-5 of Fig. 4;; Fig. 6 is a sectional view on the line 6-43 of Fig. 4; Fig. 7 is a sectional view' on the line of Fig. i; and i Fig. 8 is a sectional view on the line 8-8 ofFig.4.

, My invention, in the form-thereof illustrated in the drawings,- comprises aftubular case or housing body 1, provided with the supporting lugs 1", the cap 1, and the bot tom 1; the parts of the case being formed of suitable insulating material such as porcelain. o

A conducting cap or cap plate 2, provided with tllGdlSllGClCGIltQl' 2 with clips 2 cut therefrom, has its periphery engaged between thetop ofthe body 1 and the cap 1',

and its peripheral lug 2? (for connecting it Wltll. the conductor 3 leading from the line wire) disposed in the offset recess 1? of the cap; the cap being locked to the body on the plate by bayonet joint comprising the body lugs'l which engagein the an .gular cap ways 1 and sealed; by the ce- .ment 1.

V A resistor 4, of non-inductive character, has its upper end engaged by the clips 2 of the conductor 2' and] its lower end engaged with conducting caplor cap. plate 5 by its clips 5. Theresistoristhus,by the cap plates 2 andf5, heldcentrally in the upper part of the compartment .1 of the case,

which is adapted for" holdinga fluid,vparutilized for creating theblast;

Similar conducting plates, dished to proticularly air, to beheated, expanded and .vide the bodies 6 combined with oppositely inclined conical parts 6' and 6 forming concentric annular edges '6, are separated by the insulators 7 having their ends in engagement with the flat bodies and act- 'ing to hold them in the desired relation,

with the annular edges 6 separated to provide air gaps, the plates being held in alinement by the ribs 1 of the body 1. A base 6 is held in engagement with the plate 5'and the several plates are held together and to the insulators 7 by a coiled spring 8 which bears against the base of the lower plate and the inwardly projecting radial fins 1 of an insulating step 1 which is seated in the hollow bottom or bottom plug 1, the part 1 containing the central conical hole 1 A stem 9, of conducting material, is fixed to the body 6 of the lower plate and passes through the spring and the member 1 being held in the desired central position by engagement with the bearings 1 A. metal tube 10 extends through the plug 1, concentrically with the terminal memher 9, and is so spaced therefrom as to form an annular air gap between the terminals 9 and 10. The tube is provided with an annular flange or plate 10 which is fixed between the bottom of the recess in the plug and the bottom of the member 1 the, parts 1 and l being fixed together by cement 1". The ground conductor 11 is held in an aperture l in the plug 1' in engagement with the plate 10*.

The plug 1 is locked in place by a bayonet joint comprising the lugs 1 thereon which enter the angular ways 1 of the body 1 and the parts are sealed by cement 1.

When the line is overcharged, a discharge to ground takes place through the parts 3,2, 4, 5, 6, 9, 10 and 11, the heat generated by the passage of the discharge through the resistor a and across the gaps between" the terminals 6 heating and expanding the fluid in the compartment 1 the fluid dischar ing under the pressure in a blast around the cylindrical terminal 9 through the tubular terminal 10, destroying the arc across the gap and sweeping away the ionized air forming a path for the fiow of normal current following the discharge.

It being known that a given air gap distance will resist a certain voltage or electrical pressure without breaking down or arcing over, the space and number of the air gaps are made such that their summation equals a total air gap space which would not break down under normal voltage but will break down under excessive voltages, liable to injure the apparatus.

lVhen a discharge takes place as a result of excessive voltage, and normal current follows the discharge by reason of the ionization of air, the flow of currentis interrupted, if small, at the first half cycle of the generator wave, or where the flow reverses in direction and passes through zero value. But otherwise the heat, developed by the current passing through the resistor and the arcs across the air gaps, expands the surrounding air confined within the case so that its only escape is through a contracted passage, which increases the velocity of its escape and applies the force of the blast most effectively for obtaining the result desired.

The mechanism described permits the use of comparatively low rcsistance,'just high enough to limit the flow of dynamic current following the lightning discharge to ground without producing serious voltage disturbances' on the circuit, or causing lamps connected therewith to flicker or wink, or tripping out circuit breakers or fuses in generator stations, or decreasing the efliciency of protection from lightning.

Having described my invention, I claim:

1. A lightning arrester comprising a casing containing a'chamber having a restricted outlet, conductors having an air gapbetween them in said outlet, and insulated conducting plates in said chamber, one of said conductors being supported by one of said plates and said plates having separated edges forming one or more air gaps. l

2. In apparatus of the character described, a casing containing a chamber having a restricted outlet, in combination with means comprising conductors having between them an air gap in the atlrof a blast through said outlet, a plurality'of conducting plates in saidchamber having air gaps between them, and resilient means for holding said plates in position. i

In testimony whereof I have hereunto set my name this 20th day of October, 1916.

JOHN ROBERT MCFARLIN;

Copies of this patent may be obtained for five cents each, by addressing the Commiss ioner of Patents,

, -Washington, D. 0. i 

